Question

The average score on a standardized test is 500 points with a standard deviation of 50 points. What is the probability that a student scores between 450 and 600 on the standardized test?

98%

82%

16%

2%

Answer 1

450 is 1 std deviation from 500 and 600 is 2 std deviations. So what you wanna do is for plus and minus 1 std deviation the probability is something like ~67% but you want halve of that. so for the 450 bit its 33%.

Then for 2 std deviations plus minus its ~90ish%, but you want the the plus side, so you divide ~95ish% by 2 and get 48ish%.

so then you add 33% and 48% to get B

Also my standard deviations % are off the top of head so you will wanna check them :)

Answer 2

Thank you!

Answer 3

This is from wikipeda showing the percentages for each standard deviation

http://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/Standard_deviation_diagram.svg/350px-Standard_deviation_diagram.svg.png

if you add for the regions -1sigma to 2sigma you get 81.8%

Answer 4

no problems :)